Photographic development equipment



June 25, 1963 H. 1. SMITH 3,094,914

PHOTOGRAPHIC DEVELOPMENT EQUIPMENT Filed April 6, 1959 2 Sheets-Sheet 1 IN V EN TOR.

June 25, 1963 H. l. SMITH 3,094,914

PHOTOGRAPHIC DEVELOPMENT EQUIPMENT Filed April 6, 1959 2 Sheets-Sheet 2 IN V EN TOR.

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United States Patent 3,094,914 PHOTOGRAPHIC DEVELOPMENT EQUIPMENT Harold I. Smith, Pasadena, Calif, assignor, by mesne assignments, to Consolidated Electrodynamics Corporation, Pasadena, Calif., a corporation of California Filed Apr. 6, 1959, Ser. No. 804,338 6 Claims. (Cl. 95-89) This invention is concerned with apparatus for rapidly and continuously developing successive portions of a strip of photographic material, such as an oscillograph record. It provides improvements in apparatus of the type described and claimed in co-pending applications Serial No. 681,804 filed September 3, 1957, by Robinson et al., and now abandoned, and Serial No. 712,148, now Patent No. 2,983,250, filed January 30, 1958, by Godfrey.

In the apparatus described in the aforementioned applications, long flexible strips of photographic material, such as paper coated on one side with a photosensitive emulsion, are unwound from a feed reel, drawn past a camera mechanism, such as an oscillograph that throws a moving beam of light across the moving strip, thence past an applicator that places a thin film of developing fluid on the layer of exposed emulsion, and thence over a drying means such as a heated platen that drives the wetted emulsion film quickly and fixes it sufficiently that it can be withdrawn from the light-proof box in which the strip is exposed. In consequence of this procedure, oscillographic records and the like can be examined within seconds after they are made. This represents an immense saving of time and a great convenience in the interpretation of oscillographic records produced in wind tunnel and flight testing operations, and the apparatus described and claimed in the foregoing applications has achieved outstanding success. Several hundred of the apparatus are now in use in research and testing facilities of aircraft manufacturers and the US. Government.

In the apparatus described and claimed in the aforementioned applications, the applicator for the developing liquid comprises a movable fluid reservoir member having a narrow longitudinal slit in one wall that extends across the photographic strip when the applicator is in operative position. When the apparatus is not operating the applicator is tipped so that the slit opens upwardly out of engagement with the strip. Otherwise it leaks.

To assure that the applicator for the developing liquid will be in operative position when the photographic strip is being exposed and the apparatus is in operation, an electrical interlock or switch is provided which prevents the rest of the equipment from functioning until the applicator is moved into contact with the emulsion layer on the strip. The movement of the applicator is accomplished manually.

Recently, it has become desirable to operate equipment of the type described in the aforementioned applications by remote control. In such cases it is not feasible to tip the applicator in and out of engagement with the strip manually each time the apparatus is stopped. The tipping can be accomplished by means of a motor with a remote control, but this adds to the complexity and cost of the apparatus.

A further disadvantage of the applicator heretofore employed resides in the fact that at slow linear strip speeds, say those below 0.5 inch per second, the applicator tends to deposit too much developing liquid on the emulsion. This leads to drying difiicul-ties and also may cause the record to be fogged.

I have overcome the foregoing difficulties and have adapted to apparatus of the typeunder consideration to remote control by a simple change which does not involve the use of any additional motors and permits the 3,094,914 Patented June 25, 1963 lCE applicator to remain stationary and in contact with the photographic strip whether or not the apparatus is in operation. In consequence, the electrical interlock may also be eliminated from the apparatus, to the end that my apparatus suitable for remote control is actually simpler than the examples heretofore available.

In accordance with my invention I equip apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of photographic material and means for drying the successive portions rapidly thereafter with a combination which comprises a member (the applicator) having an openended slit, means for supplying the liquid to the slit, a resilient body disposed adjacent the open end of the slit and extending along it and pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit between the open end of the slit and the resilient body with the photosensitive layer disposed toward the slit, so that the photosensitive layer is pressed against the open end of the slit as the strip moves across it. The same means for moving the strip between the applicator and the resilient body is also employed to carry the strip subsequently to and preferably through the drying means.

In the improved apparatus of my invention the applicator, if desired, may be made stationary. In any case, there is no need for the interlock switch heretofore employed to prevent the rest of the apparatus from being operated unless the applicator is in contact with the photographic strip. In other words, the applicator may be left in contact with the strip at all times without fear of leakage. Moreover, the linear strip speed may be reduced as low as 0.1 inch per second without excessive application of developing liquid. The improved apparatus, therefore, is less complex and moreversatile than that heretofore available. Moreover, it is admirably adapted to operation with remote control, since the applicator does not have to be moved in and out of engagement with the photographic strip.

For most developing liquids I prefer to employ a slit about 0.004 inch Wide at the point where the applicator comes in contact with the emulsion. With such slits I prefer to employ a resilient body having a hardness of about 30 durometer or equivalent. For the particulars of rubber hardness measurement, reference is had to Identification of Rubber by Means of a Durometer, ASTM standards, 1955, page 1096, describing durometer measurements according to ASTM D676-55T specifications. The body may be a stationary member, but in such case it should prevent a slick surface to the strip that slides over it. A rubber pad having a layer of polytetrafluoroethylene resin (Teflon) is satisfactory. However, I prefer to employ a resilient member in the form of a rotatable roller, that rotates as the strip is drawn past it. For slits having a width of .003 to .005 inch, I have found that a roller having a diameter ranging between one and two inches is satisfactory. Such a roller may have a durometer hardness from about 25 to about 35. The durometer measurement cannot be made on a resilient member in the form of a pad but substantially the same degree of softness should be achieved.

These and other aspects of my invention will be completely apparent in the light of the following detailed description of presently preferred examples, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram illustrating a complete apparatus of the type heretofore described provided with a slit-type applicator and a resilient rotatable roller;

FIG. 2 is an enlarged elevation, partly in section, of the applicator and roller of FIG. 1; and

FIG. 3 is an elevation, partly in section, similar to that 3 of FIG. 2, but with a slick-surfaced resilient pad substituted for the roller.

The apparatus of FIG. 1 comprises a magazine 1b which encloses the apparatus save at a long narrow side Window 11 through which a moving light beam 12 produced by a conventional galvanometer (not shown) enters the magazine through a collimating lens 13. The light beam moves back and forth perpendicular to the plane of the paper in FIG. 1.

The magazine houses a supply roll 14 on which an unexposed strip of photographic paper 15 is mounted. This strip is unrolled and carried over a metering roller 16 disposed opposite the exposure window. The metering roller is driven by conventional means (not shown) to determine the speed of travel of the strip through the magazine. From the metering roller the strip is carried around an idling or tensioning roller 17 and thence past a developing solution applicator 18, which is shown in greater detail in FIGS. 2 and 3. The applicator has a reservoir '19 which feeds a conduit member 20. This member communicates with the reservoir through a conduit that has a narrow slit 21 at its outer end, the length of the slit being perpendicular to the plane of the paper in FIG. 1. The photographic strip passes across and is bent slightly over the open end of the slit and is pressed against it by a rotatable resilient idler roller 22 mounted on a shaft 23.

From the applicator the photographic strip is carried across the curved face 24 of a drying platen which is heated by a thermostatically controlled electrical means (not shown). From the platen the strip is passed through a pair of compression rollers 25, 26, the lower roller 26 being driven through a slip clutch (not shown) to maintain a constant tension on the strip between the metering roller and the compression rollers. After passing through the compression rollers the strip is discharged through a conventional exit slit 27 in developed and fixed condition ready to be inspected.

The photographic strip carries a layer of emulsion (not shown in FIG. 1) which is on the side of the strip adjacent the collimating lens when the strip passes this exposure point. Consequently, the exposed emulsion layer is also adjacent the open end of the slit applicator as it passes this apparatus.

As the strip passes the collimating lens it is exposed to the moving light beam to form an undeveloped photographic trace on the strip. The reservoir is filled with an aqueous developing solution which is applied by means of gravity feed from the reservoir 19 through the slit 21 to the photographic paper 15 as a very thin film that is only sulficient to develop and wet the emulsion without substantially wetting the backing paper. The light trace on the paper is thus subjected to development and thereafter it is dried immediately in passing over the platen. This stops the action of the developer and fixes the record sufficiently to permit its inspection in daylight as soon as it issues from the magazine through the exit slit.

Referring now to FIG. 2, the applicator 18 comprises a cylindrical drum having closed ends 28 and a filling aperture covered by a vented cap 29. The drum is mounted on a concentric horizontal shaft '30 so that it can be rotated on its own major axis. The bottom of the drum is fitted on the outside with an adaptor 31 to which the circuit member is fastened. A passageway 33 communicates from the bottom of the drum through the adaptor to a cavity 34 within the conduit member. The conduit member is formed of an upper piece 35 and a lower piece 36 held together by screws or other fastening means (not shown). A narrow slit 37 opens out of the applicator at its pointed end 38. As previously indicated, the photographic strip 1'5 is drawn past and bent over the pointed end of the conduit member as the strip passes through the magazine.

As shown in FIG. 2 the exposed emulsion layer 15A on the backing paper 15B of the photographic strip is adjacent the slit opening in the applicator so that it is wetted with developing solution. A resilient rubber roller 39 is disposed immediately adjacent the open end of the slit applicator so that it presses resiliently against the open end of the applicator and holds the moving strip against the slit of the applicator to prevent leakage. The resilient roller is rotatably mounted on an idler shaft 40.

The slit applicator proper is provided with a removable shim 41. By employing shims of different thicknesses, the width of the slit at the open end of the applicator may be adjusted.

If desired, the entire applicator may be tipped up so that the pointed end moves up counterclockwise to disengage from the strip When the apparatus is not in use. Thus, the pointed end can be rotated upward until it is above the level of lquid in the reservoir 19 to effectively prevent leaks when the apparatus is shut down for a long time or when a new photographic strip is being threaded through the apparatus.

Ordinarily the width of the slit will be adjusted so that it is about 0.004 inch. As previously indicated, for slits of this magnitude, the resilient roller should have a diameter ranging between one and two inches, a diameter of 1 A to 1% inches being preferred.

The apparatus of FIG. 3 is identical with that of FIG. 2, like parts being shown by like reference characters, except that the rotatable resilient roller is replaced by a resilient pad 42 of rubber or the like having a layer 43 of a slickasurfaced plastic, such as Teflon, which bears against the paper backing of the record strip and presses the exposed emulsion layer against the open end of the slit. The pad is held in position by a holder 44 which may be moved slightly by conventional means (not shown) to increase or decrease the pressure exerted by the pad against the record strip and the open end of the slit in the applicator.

Similarly, if desired, adjusting means (not shown) may be provided to move the resilient roller slightly toward and away from the pointed end of the applicator in FIG. 2, so as to adjust the pressure that the roller exerts on the record strip passing over the open end of the applicator. The pressure exerted by the resilient member against the slit is measured in terms of static indentation of the member as produced by the applicator blade. With a blade of .010 inch nominal thickness, a rubber roller of approximately 30 durometer hardness should be urged against the blade with such force as to produce a static indentation of .012 inch to .015 inch. This parameter may be varied with variations in hardness of the resilient body and in characteristics of the paper from about .007 inch to about .018 inch.

As I have already indicated, it is not essential that the applicator be made so that it is movable, but this is convenient when threading a photographic strip through the magazine or during long shut-down periods.

I claim:

1. In apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of wettable backing material and means for drying the successive portions rapidly thereafter, the combination which comprises a member having an open-ended slit, means for supplying the liquid to the slit in the member by means of gravity feed, a resilient body disposed adjacent the open end of the slit and extending along it and pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit and bending the strip over the slit as the strip passes between the slit and the resilient body with the photosensitive layer disposed toward the slit and thence to the drying means, said slit having a width selected to control the flow of liquid therethrough so that the liquid wets the photosensitive layer without substantially wetting the wettable backing material.

2. In apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of wettable backing material and means for drying the successive portions rapidly thereafter, the combination which comprises a member having an open-ended slit, means for supplying the liquid to the slit in the member by means of gravity feed, a resilient rotatable roller disposed adjacent the open end of the slit and extending along it and pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit and bending the strip over the slit as the strip passes thereacross between the slit and the resilient roller with the photosensitive layer disposed toward the slit and thence to the drying means, said slit having a width selected to control the flow of liquid therethrough so that the liquid wets the photosensitive layer without substantially wetting the wettable backing material.

3. In apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of wettable backing material and means for drying the successive portions rapidly thereafter, the combination which comprises a member having an open-ended slit, means for supplying the liquid to the slit in the member by means of gravity feed, a resilient slick-surfaced pad disposed adjacent the open end of the slit and extending along it and pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit between the open end of the slit and the slick surface of the resilient pad with the photosensitive layer disposed toward the slit and thence to the drying means, said slit having a width selected to control the flow of liquid therethrough so that the liquid wets the photosensitive layer without substantially wetting the wettable backing material.

4. In apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of wettable backing material and means for drying the successive portions rapidly thereafter, the combination which comprises a member having an open-ended slit, means for supplying the liquid to the slit in the member by means of gravity feed, a resilient pad having a layer of slick-surfaced polytetrafluoroethylene resin disposed adjacent the open end of the slit and extending along it with its polytetrafluoroethylene surface pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit between the open end of the slit and the slick surface of the resilient pad with the photosensitive layer disposed toward the slit and thence to the drying means, said slit having a width selected to control the flow of liquid therethrough so that the liquid wets the photosensitive layer without substantially wetting the wettable backing material.

5. In apparatus having means for applying liquid to successive portions of a photosensitive layer on a flexible strip of photographic backing material and means for drying the successive portions rapidly thereafter, the combination which comprises a member having an openended slit about .004 inch wide, means for supplying the liquid to the slit in the member by means of gravity feed, a resilient body rotatable roller having a diameter between one and two inches disposed adjacent the open end of the slit and extending along it and pressing toward it, and means for moving the strip lengthwise of itself and transverse to the length of the slit and bending the strip over the slit as the strip passes thereacross between the slit and the resilient body with the photosensitive layer disposed toward the slit and thence to the drying means.

6. The method of applying processing liquid to successive portions of a photosensitive layer supported on a wettable backing comprising forming, in a conduit, a slit of substantially .004 inch width and of length at least substantially the same as the width of the photosensitive layer, connecting the conduit to a source of processing liquid to be applied so that liquid is fed from the source through the conduit and to the slit by the force of gravity, resiliently pressing the photosensitive layer against the slit so that the photosensitive layer separates the slit from the backing while bending the photosensitive layer over the slit, and moving successive portions of the photosensitive layer past the slit so as to wet the photosensitive layer without wetting the backing.

References Cited in the file of this patent UNITED STATES PATENTS 2,439,802 Francis Apr. 20, 1948 2,661,292 Land Dec. 1, 1953 2,681,294 Beguin June 15, 1954 2,774,327 Saint-Hilaire Dec. 18, 1956 2,796,846 Trist June 25, 1957 

1. IN APPARATUS HAVING MEANS FOR APPLYING LIQUID TO SUCCESSIVE PORTIONS OF A PHOTOSENSITIVE LAYER ON A FLEXIBLE STRIP OF WETTABLE BACKING MATERIAL AND MEANS FOR DRYING THE SUCCESSIVE PORTIONS RAPIDLY THEREAFTER, THE COMBINATION WHICH COMPRISES A MEMBER HAVING AN OPEN-ENDED SLIT, MEANS FOR SUPPLYING THE LIQUID TO THE SLIT IN THE MEMBER BY MEANS OF GRAVITY FEED, A RESILIENT BODY DISPOSED ADJACENT THE OPEN END OF THE SLIT AND EXTENDING ALONG IT AND PRESSING TOWARD IT, AND MEANS FOR MOVING THE STRIP LENGTHWISE OF ITSELF AND TRANSVERSE TO THE LENGTH OF THE SLIT AND BENDING THE STRIP OVER THE SLIT AS THE STRIP PASSES BETWEEN THE SLIT AND THE RESILIENT BODY WITH THE PHOTOSENSITIVE LAYER DISPOSED TOWARD THE SLIT AND THENCE TO THE DRYING MEANS, SAID SLIT HAVING A WIDTH SELECTED TO CONTROL THE FLOW OF LIQUID THERETHROUGH SO THAT THE LIQUID WETS THE PHOTOSENSITIVE LAYER WITHOUT SUBSTANTIALLY WETTING THE WETTABLE BACKING MATERIAL. 